According to DE-C1-3922732, a device for fastening electric equipment on an adapter that is connected to a bus bar and features rigidly arranged terminals on the adapter for the electric equipment is shown. The electric equipment is provided with device terminal clamps and clamping shoes and can be snapped onto a mounting rail that is attached to a spacer block. The spacer block itself can be slid and locked in the adapter guide receptor which is situated perpendicularly to the bus bars. The distance between the terminal contacts which are rigidly mounted on the adapter and the guide receptor is adjusted to the maximum distance between the guide receptor and the equipment terminal clamps. It is achievable to always bring the terminal clamps of devices with different heights on the same level with the rigidly arranged terminal contacts of the adapter by using spacer blocks of different heights, whereby the device terminal clamps can be electrically connected with the terminal contacts by means of sliding the equipment which is snapped onto the spacer block towards the terminal contacts. A disadvantage of this arrangement is that the adapter must be manufactured with a guide receptor, in order to facilitate sliding and repositioning of the spacer block that is provided with a mounting rail. This adapter cannot be retrofitted with a mounting rail that can be slid and locked. Preclusion of retrofitting is also obvious by the fact that the index notches which are required for locking, must be shaped during manufacture of the adapter body itself. Additionally, utilization of the adapter is possible only up to the equipment size that is planned for the adapter, because of the rigidly chosen distance between the guide receptor and the terminal contacts of the adapter. In this arrangement, the equipment terminal clamps must not be positioned higher than the fixed adapter terminal contacts, because otherwise, connection with the equipment terminal clamps by means of sliding the equipment to the terminal contacts is no longer possible. Furthermore, a suitable spacer block must be available for each equipment size. In order to achieve release from the locked status, a locking element is provided between the spacer block and the index notches of the adapter, but it is difficult to access. The lock release status must be maintained during the entire motion of moving the spacer block in the direction for closing the contacts with the electric equipment, as well as during the reverse motion. The spacer block is locked on the adapter in both directions, and is releasable.
Another bus bar adapter is known from DE-U1-9107327. On this bus bar adapter, a plug terminal for the external input and/or output connections is mounted, and is connected to the internal wiring of the electric equipment that is mounted on the adapter. The disadvantage of this arrangement is that the bus bar adapter must be provided during manufacture for mounting of the plug terminal. This adapter can be retrofitted only if the adapter itself features special provisions for the installation of a terminal plug. Furthermore, the terminal plug provided in this arrangement is plugged in longitudinal direction of the bus bar adapter, so that maintenance of a locking system as required for a switching device is no longer possible due to the additional space requirement for the plug. In addition, installation of the terminal plug on the adapter requires a relatively extensive effort.
The task of the present invention is to develop a device of the previously mentioned kind, that can be retrofitted by simple means with a mounting rail that can be slid and is lockable, also used for fastening different sizes of equipment without limitation, and features a locking system that is simple to operate and to release for connecting to the terminals of the equipment attached to the mounting rail.